using Module.NavigationTool.Editor.Toolbar;
using UnityEditor;
using UnityEngine;

#if UNITY_2021_1_OR_NEWER
using UnityEngine.UIElements;
#endif

namespace Module.NavigationTool.Editor
{
    [InitializeOnLoad]
    internal static class ToolbarDrawer
    {
        private static bool IS_INITIALIZED;
        private static AbstractToolbarDrawer[] DRAWERS;

        static ToolbarDrawer()
        {
            EditorApplication.update -= OnEditorUpdate;
            EditorApplication.update += OnEditorUpdate;
        }
        
        private static void OnEditorUpdate()
        {
            if (!IS_INITIALIZED)
            {
                DRAWERS = ToolbarUtility.GetAllDrawers();
                
                #if UNITY_2021_1_OR_NEWER
                ToolbarUtility.OnUpdate(OnCreateElements);
                #else
                ToolbarUtility.AddGuiListener(OnGUI);
                #endif
                
                IS_INITIALIZED = true;
            }

            for (var i = 0; i < DRAWERS.Length; i++)
            {
                DRAWERS[i].Update();
            }
        }

        #if UNITY_2021_1_OR_NEWER
        private static void OnCreateElements(VisualElement leftAlign, VisualElement rightAlign)
        {
            const float HEIGHT = 22.0f;

            for (int i = DRAWERS.Length - 1; i >= 0; i--)
            {
                AbstractToolbarDrawer drawer = DRAWERS[i];
                var rect = new Rect(0.0f, 0.0f, drawer.CalculateWidth(), HEIGHT);
                drawer.Setup(rect);
                
                var container = new IMGUIContainer(drawer.OnGUI);
                container.style.width = rect.width;

                if (drawer.Placement == EToolbarPlacement.Left)
                    leftAlign.Add(container);
                else
                    rightAlign.Add(container);
            }
        }
        #else
        private static void OnGUI()
        {
            const float Y = 5.0f;
            const float SPACING = 4.0f;
            const float HEIGHT = 22.0f;
            const float PLAY_BUTTON_EXTENT = 75.0f;
            const float PLAY_BUTTON_OFFSET = -23.0f;

            if (DRAWERS == null)
                return;
            
            float xLeft = EditorGUIUtility.currentViewWidth * 0.5f + PLAY_BUTTON_OFFSET - PLAY_BUTTON_EXTENT;
            float xRight = EditorGUIUtility.currentViewWidth * 0.5f + PLAY_BUTTON_OFFSET + PLAY_BUTTON_EXTENT;

            for (var i = 0; i < DRAWERS.Length; i++)
            {
                AbstractToolbarDrawer drawer = DRAWERS[i];

                GUI.enabled = drawer.Enabled;
                float width = drawer.CalculateWidth();
                
                Rect rect;

                if (drawer.Placement == EToolbarPlacement.Left)
                {
                    rect = new Rect(xLeft - width, Y, width, HEIGHT);
                    xLeft -= width + SPACING;

                    // Note: Magic number for closest right-most item left of play button (2020.3)
                    if (rect.xMin < 414.0f)
                        continue;
                }
                else
                {
                    rect = new Rect(xRight, Y, width, HEIGHT);
                    xRight += width + SPACING;

                    // Note: Magic number for closest left-most item right of play button (2020.3)
                    //       If you don't have collab, which no sane person has
                    if (rect.xMax < 642.0f)
                        continue;
                }

                drawer.Setup(rect);
                drawer.OnGUI();
            }
            
            GUI.enabled = true;
        }
        #endif
    }
}